Booking.com once again trying their best to get out of a refund

I'm unfortunately also part of the group where Booking.com is delaying my refund, doing everything in their ability to deny me my refund, and ultimately *****ing my money.

I arrived at my Booking.com stay, only to find that this apartment is occupied. After contacting the call center, my stay got cancelled. They were helpful to get me a new stay for the night, and made a lot of empty promises on I will not be financially affected by their incompetence/negligence, and that the amount I initially paid will be my final amount paid.

It's been three weeks of trying to get my refund, with no success. Trying everything in their might to deny me my refund, but I won't be stopping until I get my money back.